[X86][NFC] Add a `use-aa` feature.

Summary:
This allows enabling useaa on the command-line and will allow enabling the
feature on a per-CPU basis where benchmarking shows improvements.

This is modelled after the ARM/AArch64 target.

Reviewers: RKSimon, andreadb, craig.topper

Subscribers: javed.absar, kristof.beyls, hiraditya, ychen, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67266

llvm-svn: 371989

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86Subtarget.h b/llvm/lib/Target/X86/X86Subtarget.h
index ce926b40ac3..4d7495641d9 100644
--- a/llvm/lib/Target/X86/X86Subtarget.h
+++ b/llvm/lib/Target/X86/X86Subtarget.h
@@ -427,6 +427,9 @@ protected:
   /// Use software floating point for code generation.
   bool UseSoftFloat = false;
 
+  /// Use alias analysis during code generation.
+  bool UseAA = false;
+
   /// The minimum alignment known to hold of the stack frame on
   /// entry to the function and which must be maintained by every function.
   unsigned stackAlignment = 4;
@@ -741,6 +744,7 @@ public:
            X86ProcFamily == IntelTRM;
   }
   bool useSoftFloat() const { return UseSoftFloat; }
+  bool useAA() const override { return UseAA; }
 
   /// Use mfence if we have SSE2 or we're on x86-64 (even if we asked for
   /// no-sse2). There isn't any reason to disable it if the target processor